Solution for testing Kafka streams

[andrus]

Looks like Kafka provides a testing framework for the client and streams that does not require starting a broker. It is based on the following "test" modules:

<dependency>
    <groupId>org.apache.kafka</groupId>
    <artifactId>kafka-streams</artifactId>
    <classifier>test</classifier>
</dependency>

<dependency>
    <groupId>org.apache.kafka</groupId>
    <artifactId>kafka-clients</artifactId>
    <classifier>test</classifier>
</dependency>

as well as ProcessorTopologyTestDriver. We need to research that and see if we can provide either a test module or a recipe to use Kafka API for testing, integrating the modules above with BQTestFactory.

There are also third-party Scala "embedded Kafka" libraries. Not sure how applicable they are for testing in Java.